ORACLE_HOSTNAME 未定义

The issue can be reproduced at will with the following steps:
1. Change the hostname.
2. Check DBConsole status 

ISSUE VERIFICATION
==================
Verified the issue referencing data collected records as noted below. 
CAUSE DETERMINATION
===================
The issue is caused by the following setup: hostname changed. 
CAUSE JUSTIFICATION
===================
This issue is described in Metalink Note 330130.1 
PROPOSED SOLUTION(S)
====================
Recreate the DBConsole 
PROPOSED SOLUTION JUSTIFICATION(S)
==================================
After the hostname changes the DBConsole must be recreated to update the repository tables. 
SOLUTION / ACTION PLAN
======================
-- To implement the solution, please execute the following steps::
Prepare the environment: 
- Open a new terminal window.
- Go to the Oracle installation folder.
- Set the ORACLE_HOME variable according to that folder.
eg. export ORACLE_HOME=/opt/oracle/db1 
Please follow the steps below. 
1. Stop the dbconsole on the target node 
$ORACLE_HOME/bin/emctl stop dbconsole 
2. Delete the repository and directory structure using EMCA: 
- go to $ORACLE_HOME/bin
- at the command prompt, enter the following command:
$PROMPT> emca -deconfig dbcontrol db -repos drop
- follow the instructions on the screen 
3) If this returns successfully please go to step 5, otherwise follow step 4. 
4) If the EMCA returns in any error please remove the repository manually: 
4.1) Logon SQLPLUS as user SYS and drop the sysman account and management objects: 
A. drop user sysman cascade;
B. drop role MGMT_USER;
C. drop user MGMT_VIEW cascade;
D. drop public synonym MGMT_TARGET_BLACKOUTS;
E. drop public synonym SETEMVIEWUSERCONTEXT; 
5) After repository deletion please recreate the repository and directory structure. 
- go to $ORACLE_HOME/bin
- at the command prompt, enter the following command:
$PROMPT> emca -config dbcontrol db -repos create
- follow the instructions on the screen 
6) In case the dbconsole startup fails please provide the files of folder
$ORACLE_HOME/cfgtoollogs
and
$ORACLE_HOME/_/sysman/log
to metalink. 
  
然后,进行em后,界面出来了,但报了一个错:
java.lang.Exception: Exception in sending Request :: null 
[oracle@oracle config]$ pwd
/op/oracle/product/10.2.4/oracle_orcl/sysman/config
[oracle@oracle config]$ vi emd.properties 
把该值修改为：agentTZRegion=Asia/Chongqing 
关于时区的列表参考：10.2.0\db_1\sysman\admin\supportedtzs.lst
然后，重启OracleDBConsole